Frequency-changer apparatus



, Dec. 4, 1928.

1,694,296 w. WEILER FREQUENCY CHANGER APPARATUS Filed A ril 16, 1927 Inventor Wilhelm Weilef b His Attorney Patented Dec. 4, 1928.

UNITED STATES WILHELM WEILER, OF NIEDERSCHONHAUSEH, GEP GENERAL ELECTRIC COMPANY, A CORPGRATIOH On NY, ASSIGNOR TO iEVV YORK.

FREQUENCY-CHANGER APPARATUS.

Application filed April 16, 1927, Serial No. 184,215, and. in Germany May 15, 1926.

My invention relates to frequency changers for transmitting power between difteren alternati .g current systems in which one of the machines of the set is of the asynchronous type and is provided with dynamo-electric regulating apparatus connected in its secondary circuit for controlling the load. In such an installation where the induction machine operates below its synchronous speed, power is given out or absorbed by the induction motor secondary depending upon whether it operates as a motor or as a generator. Herctofore this regulating power has been transferred back or taken from the line to which the primary winding of the induction machine is connected and was utilized solely for the regulation of the induction machine.

In accordance with my invention the power used for load regulation is transferred from one of the two power systems to the other through the induction machine in the same direction as power is transferred through the main set itself. By this arrangement the capacity of the set may be reduced in proportion to the maximum power used in regulation.

The features of my invention which are believed to be novel and patentable will be pointed out in. the claims appended hereto. .F or a better understanding of my invention, reference is made in the following description to the accompanying drawing which illustrates one arrangement of the apparatus and connections for carrying out my invention.

In the drawing, 10 and 11 represent two different distribution systems which may be of the same or different frequencies which frequencies may vary somewhat with respect to each other. Between these distribution systems is connected a frequency changer set illustrated as comprising a synchronous machine 13 and an induction machine 14: mechanically connected together. The induction machine is of the wound secondary type and has a pole number which requires it to operate below its synchronous speed. The secondary is brought out to slip rings 15 and connected with dynamo-electric load regulating apparatus which is driven independently of the main set. The load regulating apparatus here illustrated comprises a synchronous converter 16 having its alternating current slip rings 17 connected to the induction motor secondary and having its direct current brushes electrically connected to a direct current machine 1.8. The machine 18 is connected with a synchronous machine 19 which also drives a direct current exciter 20 for St )plying direct current excitation to the various machines, as required. No particular type of dynan electric load regulating apparatus is re ed. For example, I nngbt employ the load regulating apparatus represented in United State. Patent 1,593,- .1.00, Gilt, or that represented in United States Patent 1,528,773, Kozisek, in which power factor control is included. However, it is essential to my invention that the machine of this regulating apparatus which transfers the load regulating power to and from the transmission line shall be connected to that transmission line other than the one to which the regulated induction machine is connected. In the apparatus represented it is essential to my invention that the synchronous machine 19 transfer the power used in regulation to and from the transmission line 1 0 instead of to and from the line 11, as has been done heretofore. Accordingly, the synchronous machine 19 is connected to the transmission line 10.

In transferring power from line 10 to line 11 the induction machine let operates as a generator below synchronous speed and it is therefore necessary for the auxiliary load regulating apparatus to supply electric energy to its secondary. Energy flows from line 10 to line 11 through the main set it self and through the load regulating apparatus and the induction machine, as represented by the full line arrows. Tn transferring power from line 11 to line 10, machine 14 operates as a motor oelow synchronism and consequently its secondary gives out power to the load regulating a 'iparatus. Power flows from line 11 to line 10 through the main set itself and also through the induction machine and load regulatir apparatus as indicated by the dotted The power thus used in regulation is tr erred from one system to the other in. the desired direction instead of merely circulating through the induction machine. Accordingly, the main machines of the set may be reduced in size and capacity by an an cunt corresponding to the maximum power used in regula tion which of course occurs at the maximum load. For example, assume it is desired to provide frequency changer apparatus be- These i transttorme action between the condary windii s. the same as prior installations, but in doii 5 lo, rori one system to the other instead it circulating through loan regniatinsr apparatus and an induction machine connectoo to the same system.

Heretotore it was always considered ocsirable from the standpoint ot econor to have the induction ma hine opera te ch to rder to reduce th the 1 ad regulating apno other function lowever it is so that where my lHTQntiOR is employeetl consideration is no longer important 7 regulating apparatus l size and ca ae t o paratus whici per orinel t .ull that of r' ulation.

its synchronous speed in the loa L 1' serves to transfer power from one system to the other in pertomning its regulating function and as its capacity is increased the capacity of the main Set mi he reduced.

In accordance with the rovisions of the patent statutes, l have described the prin ciple of operation o't my invention together with the apparatus which 1 now consider to represent the best emh ,dinicnt thereot; but I. desire to have it understood that the apparatus shown is only illustrative, am that the invention can he carried out by other means.

What l claim new and desire to secure 0 Patent of the llnitec States is:

1. In coirhination, ty *0- alternating current systems a rrequency changer set connected between saio systems comprising two mechanically connected alternating current dynamo-electric machines respectively electrically connected to said systems one oi' said machines oeing oi. the form wounc asynchronous type arranged to operate below synchronism regulating apparatus tor controlling the power supplied to or given out from the secondary of said asynchron us inaof the load trans regulating apparz: tion to E l the one chine 1 1:

regulatioi the other current nected.

In combination distribution S paratus connected l-Jccwecu 5 11i prising a synchronous war '1 one system and an connected to the otl er 5 being; mechanic haying such pole n nous machine open." said asynchronous nizicliii e wound si -contrary type. dynamo-eh regulating apparatu' V machine driven imlependcn chanically connect c said load 1' ir'onous mach illiltl'lllh toectner an asynchroused in lot:

of said asyncnronoar line and l lnition syst 111 to which sari nchrznioae; mu chine connecte In whness r s t an 

